Stratigraphic Model Predictions of Geoacoustic Properties

Geoacoustic properties of the seabed have a controlling role in the propagation and reverberation of sound in shallow-water environments. Several techniques are available to quantify the important properties but are usually unable to adequately sample the region of interest. In this paper, we explore the potential for obtaining geotechnical properties from a process-based stratigraphic model. Grain-size predictions from the stratigraphic model are combined with two acoustic models to estimate sound speed with distance across the New Jersey continental shelf and with depth below the seabed. Model predictions are compared to two independent sets of data: 1) Surficial sound speeds obtained through direct measurement using in situ compressional wave probes, and 2) sound speed as a function of depth obtained through inversion of seabed reflection measurements. In water depths less than 100 m, the model predictions produce a trend of decreasing grain-size and sound speed with increasing water depth as similarly observed in the measured surficial data. In water depths between 100 and 130 m, the model predictions exhibit an increase in sound speed that was not observed in the measured surficial data. A closer comparison indicates that the grain-sizes predicted for the surficial sediments are generally too small producing sound speeds that are too slow. The predicted sound speeds also tend to be too slow for sediments 0.5-20 m below the seabed in water depths greater than 100 m. However, in water depths less than 100 m, the sound speeds between 0.5-20-m subbottom depth are generally too fast. There are several reasons for the discrepancies including the stratigraphic model was limited to two dimensions, the model was unable to simulate biologic processes responsible for the high sound-speed shell material common in the model area, and incomplete geological records necessary to accurately predict grain-size

“后Urey模型时代”的稳定同位素地球化学基础理论

简要综述了最近十几争来稳定同位素地球化学基础理论发展的几个热点，包括能处理重元素的同位素分馏的核场效应理论、基于晶格动力学及声子的密度函数微扰理论计算的固体同位素分馏理论、稳定同位素的微观反应动力学理论，以及含压力变量的同位素分馏理论。这些新理论，表明长期基于Urey模型或称Bigeleisen-Mayer公式的稳定同位素地球化学的时代已经结束，更精确、更丰富的理论体系正在逐步建立之中。

比较型算术应用题一致性效应的实验研究

As former research shown, the error rate of consistent compare word problem (such as: Mary has 5 apples, Tom has 2 apples more than Mary, how many apples does Tom has?) is much lower than the rate of inconsistent compare word problem (such as: Mary has 5 apples, she has 2 apples more than Tom, how many apples does Tom has?). This difference of error rate is named as Consistency Effect. There are different explanations about why consistency effect happens, one of them is R.E.Mayer's opinion about two kinds of problem solving strategies. As Mayer's opinion, unsuccessful problem solvers make mistakes on inconsistent problem because they use Direct Translation Strategy, problem solvers who use Problem Model Strategy will not make such kind of mistakes. In this study, three experiments with 3~(rd) graders investigate reasons for the consistency effect. The results of experiment 1 do not support the explanation of Mayer's theory of two kinds of strategy. Experiment 2 shows that there is no relation between inconsistent problem error and Impulsivity cognitive style. Experiment 3 reveals that the working memory capacity of successful inconsistent problem solvers is significant larger than the capacity of unsuccessful solvers. It is supposed that working memory could be an important factor contributing for the consistency effect.